In a photolithography process for manufacturing of a semiconductor device, a developer is supplied to a substrate, on which a resist film has been formed and which has been exposed with a predetermined pattern, so that a resist pattern is formed on the substrate. The developing process is sometimes performed using a method, in which a puddle of a developer is formed on the entire substrate by moving a nozzle having an elongate discharge opening from one end to the other end of the substrate while discharging the developer from the discharge opening. Since the puddle is formed while the substrate is under a stationary state, this developing method is referred to as “stationary developing method”. Japanese Patent No. 3614769 (JP 3614769 B2) describes an example of the stationary developing method. There is another developing method that rotates a substrate and moves a nozzle so as to move a developer supplying position radially on a rotating substrate. Due to the movement of the developer supplying position and a centrifugal force, a liquid film of the developer is formed on the substrate and the developer forming the liquid film flows. Japanese Patent No. 4893799 (JP 4893799 B2) describes an example of the rotary developing method.
In the stationary developing method, the liquid puddle sometimes fluctuates due to various factors, such as gas flows in a circumstance where the liquid puddle is formed, and vibrations of a driving mechanism connected to a substrate holder for holding the substrate. Due to the fluctuation, concentration of the developer near the resist film may vary in various locations within the plane of the substrate, resulting in fluctuation in the reaction of the resist film and the developer. As a result, CPU (Critical Dimension Uniformity) of CD (Critical Dimension) which is the line width of the pattern in one exposure region (shot) within the wafer plane may be deteriorated.
In the rotary developing method, since the developer flows and is stirred on the substrate, CDU in the exposure region can be higher than that in the stationary developing method. However, in the rotary developing method, a developer supplied to the substrate flows on the surface of a resist film, during which the developer reacts with the resist so that the concentration of the developer changes. That is, CD may vary in the flowing direction of the developer. A technique capable of achieving a higher CDU is thus desired. Japanese patent laid-open publication No. JP2012074589A discloses a technique that brings the lower end of a nozzle disposed above a central portion of a substrate into contact with a processing liquid supplied from the nozzle and rotating the substrate thereby forming a liquid film on the substrate. This technique, however, is not capable of solving the foregoing problem.